1. Field of the Invention
The invention is based on an internal gear pump for a brake system of the kind used particularly in the hydraulic system of vehicle brake systems.
2. Description of the Prior Art
One such internal gear pump has already been disclosed for instance in German Patent Disclosure DE 19613833 B4. There the fluid is pumped in the usual way from the intake side to the pressure side of the internal gear pump in that a filler piece, tapering toward the pressure side, is disposed in a crescent-shaped annular chamber of the pump between the internal geared wheel and the pinion and which is braced by one end axially against the fluid pressure on the pressure side on a stop face. The filler piece rests with its curved inner and outer circumferential face, with radial sealing, at a plurality of tips of teeth of the pinion and of the internal geared wheel, respectively. Since the fluid volumes entrained by the sealed-off gaps between teeth of the gear wheels rotating in the same direction are brought together at the tapered end of the filler piece, the desired high pressure level results in this region of the pump. In order to attain the most effective possible sealing off of the tooth gaps in the region of the tips of teeth, the filler piece is composed of a segment holder, forming the base part, and a sealing segment that is braced movably on the segment holder; the circumferential face of the segment holder rests on the covered tips of teeth of the pinion, and the opposed circumferential face of the sealing segment rests on the covered tips of teeth of the internal geared wheel. A leaf spring arrangement with three leaf springs is also braced between the segment holder and the sealing segment and by means of it, the segment holder and sealing segment are pressed apart and thus rest with spring loading on the covered tips of teeth. In addition, the segment holder and sealing segment, under corresponding operating conditions, are pressed apart by way of a fluid pressure, equivalent to approximately half the operating pressure, since an intermediate chamber partitioned off by elastic sealing rollers of an elastomer or polymer material, located between the segment holder and the sealing segment, communicates fluidically through recesses with a pressure buildup region of the internal geared wheel. The sealing rollers engage an associated groove and must be kept in their sealing position by means of one at a time of the three leaf springs during the shifting of the sealing segment. Thus the sealing between the covered tips of teeth and the circumferential side, cooperating with them, of the segment holder and the sealing segment remains automatically operative as the pressure level of the pump increases as a consequence of an increase in the contact pressure. The geared pump is technically very complicated, especially because the filler piece is composed of many parts and the production of the internal gear pump is correspondingly expensive.